In the mining industry and in the construction of tunnels, it is common practice to utilize a support that is composed of sections and backfilled with concrete. This concrete backfill is normally reinforced with the aid of lattice trusses or girders and anchored in the rock by rock bolts. The lattice girders are usually in the form of triangular-section girders. Regardless of girder shape, tunnels or drifts can have an arc-shaped cross section or a rectangular cross section. Mine or tunnel roof supports of rectangular cross section consist of a frame with a lintel and posts of wood or steel, wherein the lintel being subject to significant bending stresses.